13. Nervous System Central Nervous System (CNS) Peripheral Nervous System (PNS) Autonomic Nervous System (ANS)(involuntary ) Somatic nervous System (voluntary) Sympathetic Nervous System Parasympathetic Nervous System
33. Sympathetic CNS ganglion short preganglionic neuron long postganglionic neuron target Parasympathetic CNS ganglion long preganglionic neuron target short postganglionic neuron Overview of the Autonomic Nervous System Differences between Sympathetic & Parasympathetic Relative Lengths of Neurons
34. Parasympathetic Overview of the Autonomic Nervous System Differences between Sympathetic & Parasympathetic Neurotransmitters ACh, + NE (ACh at sweat glands) , + / -, α & ß receptors ACh, + / - muscarinic receptors • All preganglionics release acetylcholine (ACh) & are excitatory (+) • Symp. postgangl. — norepinephrine (NE) & are excitatory (+) or inhibitory (-) • Parasymp. postgangl. — ACh & are excitatory (+) or inhibitory (-) Sympathetic • Excitation or inhibition is a receptor-dependent & receptor-mediated response Potential for pharmacologic modulation of autonomic responses ACh, +
35. Point of CNS Origin T1 L2 (thoracolumbar) Brainstem, S2 S4 (craniosacral) Site of Peripheral Ganglia Paravertebral – in sympathetic chain On or near target tissue Length of preganglionic fiber Short Long Length of postganglionic fiber Long Short
36. NT at Target Synapse Norepinephrine (adrenergic neurons) Acetylcholine (cholinergic neurons) Type of NT Receptors at Target Synapse Alpha and Beta ( and ) Muscarinic NT at Ganglion Acetylcholine Acetylcholine Receptor at Ganglion Nicotinic Nicotinic
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40. Target Organ Parasympathetic Effects Sympathetic Effects Eye (Iris) Stimulates constrictor muscles. Pupil constriction. Stimulates dilator muscles. Pupil dilates. Eye (Ciliary muscle) Stimulates. Lens accommodates – allows for close vision. No innervation. Salivary Glands Watery secretion. Mucous secretion. Sweat Glands No innervation. Stimulates sweating in large amounts. (Cholinergic) Gallbladder Stimulates smooth muscle to contract and expel bile. Inhibits gallbladder smooth muscle. Arrector Pili No innervation Stimulates contraction. Piloerection (Goosebumps)
41. Target Organ Parasympathetic Effects Sympathetic Effects Cardiac Muscle Decreases HR. Increases HR and force of contraction. Coronary Blood Vessels Constricts. Dilates Urinary Bladder; Urethra Contracts bladder smooth muscle; relaxes urethral sphincter. Relaxes bladder smooth muscle; contracts urethral sphincter. Lungs Contracts bronchiole (small air passage) smooth muscle. Dilates bronchioles. Digestive Organs Increases peristalsis and enzyme/mucus secretion. Decreases glandular and muscular activity. Liver No innervations No innervation (indirect effect).
42. Target Organ Parasympathetic Effects Sympathetic Effects Kidney No innervation. Releases the enzyme renin which acts to increase BP. Penis Vasodilates penile arteries. Erection. Smooth muscle contraction. Ejaculation. Vagina; Clitoris Vasodilation. Erection. Vaginal reverse peristalsis. Blood Coagulation No effect. Increases coagulation rate. Cellular Metabolism No effect. Increases metabolic rate. Adipose Tissue No effect. Stimulates fat breakdown.
43. Target Organ Parasympathetic Effects Sympathetic Effects Mental Activity No innervation. Increases alertness. Blood Vessels Little effect. Constricts most blood vessels and increases BP. Exception – dilates blood vessels serving skeletal muscle fibers (cholinergic). Uterus Depends on stage of the cycle. Depends on stage of the cycle. Endocrine Pancreas Stimulates insulin secretion. Inhibits insulin secretion.